Summary

Hybrid HTO showed similar accuracy in angular correction compared to OWHTO in correction angle matched cohort.

Abstract

Purpose

We tried to compare surgical accuracy between Hybrid lateral closed wedge high tibial osteotomy (hybrid HTO) and medial open wedge high tibial osteotomy (OWHTO), and verified previously reported facts regarding hybrid HTO using our data by matching correction angle between the two groups.

Methods

Fifty OWHTO patients were selected for 2:1 propensity matching with 25 hybrid HTO patients. There were 17 female (68%) and 8 male (32%) of mean 57.0±6.0 years (range 42-69) in hybrid HTO group, and 32 female (64%) and 18 male (36%) of mean 57.5±5.1 years (range 42-67) in OWHTO group. Rate of correction error was calculated by dividing the difference between the ?MPTA and preoperatively planned correction angle (?PRD) by planned correction angle. Accuracy of angular correction was assessed using the ?PRD and correction error rate. Hip-knee-ankle axis (HKA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), length of the whole lower limb and tibia was measured. Caton-Deschamp index (CDI).was used to assess change in patellar height.

Results

The discrepancy between planned correction angle and real correction angle was 0.82±2.29° in hybrid HTO and 1.05±3.42° in OWHTO (p>0.05), and the rate of error in performing osteotomy was similar between the groups with about 6% error rate. Postoperatively, radiological results including PTS (8.53±4.14° in Hybrid HTO and 13.45±4.01° in OWHTO) (p=0.000), tibia length (319.46±24.10mm in hybrid HTO and 338.00±23.60mm in OWHTO) (p=0.002), CDI (1.00±0.14 in hybrid HTO and 0.83±0.18 in OWHTO) (p=0.000) was significantly different between the two groups. The amount of change in PTS (-3.32±2.65° in hybrid HTO and 2.50±3.39° in OWHTO) (p=0.000), tibia length (-4.00mm [-5.50;1.50] in hybrid HTO and 5.55mm [0.60;16.00] in OWHTO) (p=0.000), CDI 0.02±0.14 in hybrid HTO and -0.16±0.18 in OWHTO) (p=0.000) was significantly different between the groups. Union rate of the osteotomy site was significantly faster in hybrid HTO (4.00 month [4.00;5.00]) than in OWHTO (8.00 month [6.00;8.00]) (p=0.000).

Conclusion

Hybrid HTO showed similar accuracy in angular correction compared to correction angle-matched OWHTO. Reduction in posterior tibial slope, tibial shortening, maintained patellar height relative to the proximal tibia, and faster osteotomy site union was also confirmed in this matched comparative study.